Oracle DB installer will normally use a X11-based GUI. Have you verified that your X11 connection actually works, e.g. by running "xterm &" or "xclock &" and seeing the respective application window appear on your screen?

Is the DISPLAY environment variable set correctly in the session you wish to use to run the installer?

If you are running the installation remotely from a Windows system, you'll need a "X11 server" software on your Windows system. If you are connecting to the remote system using a SSH client, you must have the "X11 forwarding" setting enabled; in most SSH clients, it is disabled by default. For example, in PuTTY, the setting is at Connection -> SSH -> X11 -> Enable X11 forwarding.

The OUI creates several log files: installlActions<timestamp>.log, oraInstall.out and oraInstall.err.

After starting the OUI, wait one or two minutes, so any un-responsive network connections get to time out and the OUI has a chance to generate error messages for them. Then look at the directories that should contain the OUI log files. Have the log files been generated? Are there any error messages in them?

If the log files don't even get created, then the OUI hangs in a very early phase. It might be caused by various reasons: for example, your /tmp directory might be getting 100% full as OUI extracts itself to it. Or if you have mounted (or auto-mounted) NFS filesystems and the NFS server is currently unreachable, those might cause the OUI to hang if e.g. the home directory of the oracle user is located on the unreachable NFS filesystem.